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Section 1 -Lect Electronics Engg

No. of Questions: 100
Duration in Minutes: 120

In thermo-couple instruments, in which of the following is an emf caused if the junction of two
wires of dissimilar metals is heated and the free or cold ends are connected to a milli-voltmeter?

Kelvin effect

Hot wire effect

Seebeck effect

Faraday effect

The largest change of input quantity for which there is no output of the instrument is called as

Dead time of that instrument
Live zone of that instrument
Dead zone of that instrument
Discrimination of that instrument

Which of the following instruments can be used for measurement of very high value resistances
such as insulation resistance in industries?

Wheatstone bridge
Megger
Ohm-meter
Resistive potentiometer

Which of the following materials is used in the construction of thermistors?

Pure metal
Pure semiconductor
Pure insulator
Sintered mixture of metal oxides

Which of the following transducers can be used for non-contact temperature measurement?

Resistance temperature detector
Thermistor
Sensistor
Pyrometer

For a NAND gate, when one or more inputs are low then the output will be

Low
High
Alternately high and low
High or low depending on relative magnitude of inputs

Which code is used in constructing k-maps?

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Hamming code
2outof5code
BCD code
Gray code

The current mode logic is same as

LSI
CMOS
TTL
ECL

What is the complement of 01101?

10010

10011

1100

1001

10) Which one of the following logic circuit has the highest speed as compared to the currently
available logic circuits?

Resistance-transistor logic
Emitter-coupled logic
Integrated-injection logic
Diode-transistor logic

11) The output of a JK flip-flop with asynchronous preset and clear inputs is The output can be
changed to with one of the following conditions by applying

J =0andusingaclock
J =0andusingtheclock
Asynchronous preset input
J K 1 and usingthe clock

12) The contents of EPROM can be erased by exposing it to

Ultraviolet rays
Infrared rays
Burst of microwaves
Intense heat radiations

13) Converting (10110110)2 to base 16 will result in

A616
B616
C616
D616

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14) Which one of the following is equivalent to
x X-OR 0
1 NOR x
x AND x
x X-NOR 0
15) The following switching functions are to be implemented using a Decoder.
The minimum configuration of the decoder should be
2 to 4 line
3 to 8 line
4 to 16 line
5 to 32 line
16) What is the steady state error of type-0 system for ramp input?
8
A/K

0
17) What is the time response of a system whose poles lie on the right hand side of s-plane?
Exponentially increasing
Exponentially decreasing
Sinusoidal oscillations
Step response
18) What will happen to the gain margin if the gain of the open loop system is doubled?
Doubled
Becomes half
Is not affected
Becomes one-fourth
19) The effect of negative feedback on distortion and bandwidth is
Both distortion and bandwidth get decreased
Both distortion and bandwidth get increased
Distortion is reduced and bandwidth is increased
Distortion is increased and bandwidth is decreased
20) Which one of the following is another name for common-collector amplifier?

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Source follower
Collector follower
Base follower
Emitter follower

21) Which of the following circuits converts any arbitrary waveform into square waveform?

Hartley oscillator
Schmitt trigger
Differentiator
RC phase shift oscillator

22) When does the Body bias effect occur in an n-channel MOSFET?

When the Source voltage is less the Bulk voltage
When the Source voltage is equal to or greater the Bulk voltage
When the Drain voltage is equal to the Bulk voltage
When the Gate voltage is equal to the Bulk Voltage

23) What is a Schmitt trigger?

A trigger circuit
A comparator with Hysteresis
A comparator without Hysteresis
Amplifier

24) What is the efficiency of Class-B amplifier?

68.50%
78.50%
88.50%
98.50%

25) A diode in which the change in reverse bias voltage varies the capacitance is called as

Varactor diode

Switching diode

Tunnel diode

Zener-diode

26) How does the cut-in voltage of diode vary with temperature?

Increases by
Decreases by
Doubles for every rise in temperature
Doubles for every drop in temperature

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27) The unity gain bandwidth of an inverting amplifier is 10 MHz What would be the bandwidth if the
gain is increased to 10
100 MHz
1 MHz
10 MHz
1 kHz
28) An inverting operational amplifier has . Its scale factor is
(symbols/notations carry their usual meaning)
1000
100
-100
-1000
29) If the base current of a BJT is 250 µA and emitter current is 15 mA, then the common base
current gain will be
0.98
0.41
59
55
30) A zener voltage regulator has load requirements of 12 V and 2 A. The zener diode minimum
current requirement is 0.2 A. The minimum voltage at input is 24 V. What is the required value of
series resistance with source?
5.45 O
6 O
7.2 O
6.38 O
31) An AC supply of 230 V is applied to a half-wave rectifier circuit through a transformer having
primary to secondary turn's ratio 12:1. The peak inverse voltage is
8.62 V
12 V
19.17 V
27.11 V
32) Consider silicon at T 300 K doped with phosphorus at a concentration of Nd 1016 cm-3. The
intrinsic concentration is given as ni 1.5 × 1010 cm-3. Calculate the thermal equilibrium hole
concentrations.
2.25×104 cm-3
5×104 cm-3
25×104 cm-3

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2×104 cm-3
33) A differential amplifier has a differential gain of 28000 and CMRR is 60 dB. What will be the
value of common mode gain?
Ac 0.125
Ac 0.33
Ac 3
Ac 28
34) The number of terminals present in IGBT is
2
3
4
5
35) How is the GTO turned off?
By using a commutation circuit
By applying reverse gate pulse
By using a latch-up circuit
By reverse anode current pulse
36) An inductor is connected in series with SCR to protect it from
Excessive high voltage
Excessive high dv/dt
Excessive high di/dt
Excessive large forward current
37) Which of the following thyristors can be used for high frequency of operation?
TRIAC
DIAC
SCR
GTO
38) The SCR would be turned OFF by voltage reversal of applied anode-cathode ac supply
frequency of
10 kHz
10 Hz
5 kHz
5 Hz
39) A certain power MOSFET has a maximum junction temperature specification of 1500o a
junction-to-case thermal resistance of 1.00 and a junction-to ambient thermal resistance of

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600 C/W. If the ambient temperature is 300o then the maximum allowable power dissipation in
the device will be
1.52 W
1.72 W
1.92W
2.00 W
40) What is the Laplace transform of step signal of 5 units magnitude?
5s
5/s
s/5
1/s
41) What is the Fourier transform of a Gaussian time pulse?
Uniform
Gaussian
Impulses
Pulse
42) What does double integration of a unit step function lead to?
A doublet
A ramp
An impulse
A parabola
43) An energy signal has 20. Its energy density spectrum is
20
100
400
800
44) The sampling rate to avoid aliasing for the signal 100 cos 200.t will be
sec
sec
sec
1/50 sec
45) The second harmonic distortion is defined as the
Ratio of amplitude of second harmonic component in the output to that of the fundamental
frequency
Harmonic distortion due to only second harmonic component
Sum of distortion of first and second harmonic components in the output

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Ratio of amplitude of fundamental component in the output to that of second harmonic
component at the input
46) As per Shannon's channel capacity theorem, if samples are transmitted in seconds over a
noisy channel which is bandlimited to Hz. The number of samples is given by
(symbols/notations carry their usual meaning)
B/T
T/B
2BT
BT/2
47) What is the frequency range of VHF electromagnetic waves?
30-300 kHz
30-3000 kHz
30-300 MHz
30-3000 MHz
48) If a signal band limited to fm is sampled at a rate less than 2fm, then the constructed signal will
be
Large in amplitude
Small in amplitude
Distorted
Distortion less
49) An SSB transmitter produces a peak-to-peak voltage of 200 V across a 100 O antenna load.
What is the Peak Envelope Power?
49.98 W
79.98 W
99.96 W
199.93 W
50) What is the channel capacity of a noisy channel with conditional probability of error p
0
1
Infinity
2
51) As per information capacity theorem, what is the capacity of channel of bandwidth Hz,
perturbed by AWGN of PSD limited in bandwidth to and transmitted power of
(symbols/notations carry their usual meaning)
C log2(P+B)
C B log2(1+P/N0B)

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C B log2(P/N0B)+1
C 2*B

52) Which waves are demodulated by Costas loop?

VSB
SSB
MSK
DSBSC

53) The total power of an AM transmitter having a carrier power of 50 W and the percentage of
modulation at 80% is

50W
66W
68W
70W

54) An AM wave has Vmax 12 and Vmin 4 V. Calculate the modulation index assuming single
tone modulation.

(symbols/notations carry their usual meaning)

2

1

1/2

1/4

55) What is the size of SP register in 8085 microprocessor?

16 bits

8 bits

64 bits

48 bits

56) What is the size of memory which can be accessed by direct accessing in 8085
microprocessor?

64kB

4kB

128 kB

128 MB

57) What is the Power Supply specification for 8085AH microprocessor?

Single +5V supply with 10% voltage margins

Dual +5V supply with 10% voltage margins

Single +10V supply with voltage margins

Dual +5V supply with voltage margins

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58) Which of the following memory is a volatile memory?

ROM
PROM
EEPROM
RAM

59) In 8085, whenever a signal is received at TRAP terminal, its program execution is transferred to
a subroutine on address

0000 H
002C H
0024 H
0004 H

60) Then number of T-states of the instruction STA in 8085 microprocessor is

10
12
13
16

61) The command line interpreter that enables the users to interact with operating system is called
the

Window

Shell

Process

Kernel

62) The average time required to reach a storage location in the memory to read or retrieve the
contents of memory is called as

Turnaround time
Latency time
Access time
Response time

63) In 8085 microprocessor, how many T-states does OPCODE FETCH machine cycle normally
require (i.e., when HOLD and WAIT signals are NOT forced)?

4to6
3to8
2 to 3
8 to 12

64) Calculate the size of memory address space for a 16 bit data and 20 bit address bus.

1MB

2MB

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3 MB
4 MB


65) The clock frequency of an 8085 microprocessor based system is 3 MHz. What should be the
minimum pulse width of the INTR signal so that it is recognized successfully?

5.6 µs
5.7 µs
5.8 µs
5.9 µs

66) In the 8085A Microprocessor, arithmetic and logical operations are performed through which of
the following?

Stack
ALU
I/O
Register

67) In a 16-bit microprocessor, a single word is

16 bit data

32 bit data

8 bit data

64 bit data

68) What are the components of system bus?

CPU Bus, Address Bus, Data Bus
Memory, Control Unit, ALU
Data Bus, Address Bus, Control Bus
Register, PC, IR

69) The 8085 Microprocessor has

8-bits Data bus and 16-bits Address bus
8-bits Data bus and 8-bits Address bus
16-bits Data bus and 16-bits Address bus
32-bits Data bus and 8-bits Address bus

70) Which of the following is a negative-resistance microwave device for oscillator applications?

IMPATT Diode
Gunn Diode
Snap diode
Schottky Diode

71) Which of the following device is used for coupling microwave energy?
Resonator

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Waveguide
Loop
Antenna

72) TWT is basically

Amplifier
An oscillator
Wideband amplifier
Tuned amplifier

73) A waveguide termination having VSWR of 1.1 is used to dissipate 100 watts of power. The
reflected power will be

0.2268 W
0.5868 W
0.3468 W
0.4568 W

74) If the drift velocity of electrons is 2x107 through the active region of length 10x10-4cm,
then the natural frequency of the diode will be

30 GHz
20 GHz
40 GHz
50 GHz

75) The nodal method of circuit analysis is based on

KVL and Ohm's law
KCL and Ohm's law
KVL and KCL
KCL, KVL and Ohm's law

76) A connected graph has number of branches and number of nodes. It's rank is

1
2
3
4

77) The term


has the dimension of

Time
Capacitance
Inductance
Resistance

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78) An independent voltage source in series with an impedance ZS=R+jXS delivers a maximum
average power to a load impedance ZL when

ZL=R
ZL=jXS
ZL R-jXS
ZL R+jXS

79) The number of loop equations required to completely analysing a network comprising of 8
independent branches and 6 nodes including the reference node shall be

3
2
4
5

80) The Z-matrix of a two port network is given by . What will be the value of (admittance
parameter)?

1.8
1.7
0.9
0.85

81) RADAR is an acronym for:

Radio Detection and Repulsion
Radio Device and Ranging
Radio Detection and Ranging
Ranging Detection and Retrieve

82) The ratio of the width to the height of the picture frame is called as

Rastar
Aspect Ratio
Length Ratio
Efficiency

83) If it takes a transmitted signal 1m sec to go up to the target and come back after reflection, how
far is the transmitter from the target?

150 Km

150m

15 Km

1500 m

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84) A pulse compression radar transmits an encoded pulse having a frequency chirp from 990 MHz
to 1010 MHz centred around 1 GHz. The range resolution capability of this radar is

7.5m

7.5 Km

75 m

750 m

85) A pulse radar has a pulse repetition frequency of 3 KHz. If the radar is emitting at 10
GHz, what is the maximum unambiguous range for this radar?

5Km

5m

50 Km

15 m

86) The colour band on the extreme left in general purpose fixed resistors represents:

Tolerance
First significant digit
Wattage Rating
Voltage Rating

87) A resistor in which the resistance changes exponentially with change in temperature is called as

Potentiometer
Phototransistor
Varactor
Thermistor

88) Which of the following is NOT a non-linear resistor?

Varistor
Precision resistor
NTC thermistor
PTC thermistor

89) In a single crystal of an intrinsic semiconductor, the number of free carriers at the Fermi level at
room temperature is:

Half the total number of electrons in the crystal
Zero
Half the number of atoms in the crystal
Half the number of free electrons in the crystal

90) The magnetic susceptibility of paramagnetic material is:

Less than zero
Less than one but positive
Greater than one

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Equal to zero
91) According to divergence theorem




92) What is the value of susceptibility in case of vacuum?
1
0.5
8
0
93) The Poynting vector is the rate of energy flow having SI Unit




94) A 50O transmission line is terminated in an impedance of 20-j50. What will be the reflection
coefficient?
0.69
1.69
6.9
16.9
95) A charged particle of mass 2Kg and charge 3C starts at point with velocity
in an electric field . At time t=1ms what will be the
acceleration of the particle

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96) Which of the following is a non-recursive system?


Y +2Y
Y
Y 2Y
5Y


97) A discrete LTI system is non-causal if its impulse response is

anU(n

an

an

anU(n


98) What is the Nyquist rate for the signal







99) If X j2} is the 4-point DFT of x what will be the DFT of



j2}

j2}

j2,

100) If the system transfer function of a discrete time system


then system is

Stable
Unstable
Stable at z=1
Unstable at z=1

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